source: mainline/kernel/arch/mips32/src/mm/tlb.c@ e40e3007

/*
 * Copyright (c) 2003-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup mips32mm        
 * @{
 */
/** @file
 */

#include <arch/mm/tlb.h>
#include <mm/asid.h>
#include <mm/tlb.h>
#include <mm/page.h>
#include <mm/as.h>
#include <arch/cp0.h>
#include <panic.h>
#include <arch.h>
#include <symtab.h>
#include <synch/spinlock.h>
#include <print.h>
#include <debug.h>
#include <align.h>
#include <interrupt.h>

static void tlb_refill_fail(istate_t *);
static void tlb_invalid_fail(istate_t *);
static void tlb_modified_fail(istate_t *);

static pte_t *find_mapping_and_check(uintptr_t, int, istate_t *, int *);

/** Initialize TLB.
 *
 * Invalidate all entries and mark wired entries.
 */
void tlb_arch_init(void)
{
        int i;

        cp0_pagemask_write(TLB_PAGE_MASK_16K);
        cp0_entry_hi_write(0);
        cp0_entry_lo0_write(0);
        cp0_entry_lo1_write(0);

        /* Clear and initialize TLB. */
        
        for (i = 0; i < TLB_ENTRY_COUNT; i++) {
                cp0_index_write(i);
                tlbwi();
        }
                
        /*
         * The kernel is going to make use of some wired
         * entries (e.g. mapping kernel stacks in kseg3).
         */
        cp0_wired_write(TLB_WIRED);
}

/** Process TLB Refill Exception.
 *
 * @param istate        Interrupted register context.
 */
void tlb_refill(istate_t *istate)
{
        entry_lo_t lo;
        entry_hi_t hi;
        asid_t asid;
        uintptr_t badvaddr;
        pte_t *pte;
        int pfrc;

        badvaddr = cp0_badvaddr_read();

        spinlock_lock(&AS->lock);
        asid = AS->asid;
        spinlock_unlock(&AS->lock);

        page_table_lock(AS, true);

        pte = find_mapping_and_check(badvaddr, PF_ACCESS_READ, istate, &pfrc);
        if (!pte) {
                switch (pfrc) {
                case AS_PF_FAULT:
                        goto fail;
                        break;
                case AS_PF_DEFER:
                        /*
                         * The page fault came during copy_from_uspace()
                         * or copy_to_uspace().
                         */
                        page_table_unlock(AS, true);
                        return;
                default:
                        panic("unexpected pfrc (%d)\n", pfrc);
                }
        }

        /*
         * Record access to PTE.
         */
        pte->a = 1;

        tlb_prepare_entry_hi(&hi, asid, badvaddr);
        tlb_prepare_entry_lo(&lo, pte->g, pte->p, pte->d, pte->cacheable,
            pte->pfn);

        /*
         * New entry is to be inserted into TLB
         */
        cp0_entry_hi_write(hi.value);
        if ((badvaddr / PAGE_SIZE) % 2 == 0) {
                cp0_entry_lo0_write(lo.value);
                cp0_entry_lo1_write(0);
        }
        else {
                cp0_entry_lo0_write(0);
                cp0_entry_lo1_write(lo.value);
        }
        cp0_pagemask_write(TLB_PAGE_MASK_16K);
        tlbwr();

        page_table_unlock(AS, true);
        return;
        
fail:
        page_table_unlock(AS, true);
        tlb_refill_fail(istate);
}

/** Process TLB Invalid Exception.
 *
 * @param istate        Interrupted register context.
 */
void tlb_invalid(istate_t *istate)
{
        tlb_index_t index;
        uintptr_t badvaddr;
        entry_lo_t lo;
        entry_hi_t hi;
        pte_t *pte;
        int pfrc;

        badvaddr = cp0_badvaddr_read();

        /*
         * Locate the faulting entry in TLB.
         */
        hi.value = cp0_entry_hi_read();
        tlb_prepare_entry_hi(&hi, hi.asid, badvaddr);
        cp0_entry_hi_write(hi.value);
        tlbp();
        index.value = cp0_index_read();

        page_table_lock(AS, true);      
        
        /*
         * Fail if the entry is not in TLB.
         */
        if (index.p) {
                printf("TLB entry not found.\n");
                goto fail;
        }

        pte = find_mapping_and_check(badvaddr, PF_ACCESS_READ, istate, &pfrc);
        if (!pte) {
                switch (pfrc) {
                case AS_PF_FAULT:
                        goto fail;
                        break;
                case AS_PF_DEFER:
                        /*
                         * The page fault came during copy_from_uspace()
                         * or copy_to_uspace().
                         */
                        page_table_unlock(AS, true);                     
                        return;
                default:
                        panic("unexpected pfrc (%d)\n", pfrc);
                }
        }

        /*
         * Read the faulting TLB entry.
         */
        tlbr();

        /*
         * Record access to PTE.
         */
        pte->a = 1;

        tlb_prepare_entry_lo(&lo, pte->g, pte->p, pte->d, pte->cacheable,
            pte->pfn);

        /*
         * The entry is to be updated in TLB.
         */
        if ((badvaddr / PAGE_SIZE) % 2 == 0)
                cp0_entry_lo0_write(lo.value);
        else
                cp0_entry_lo1_write(lo.value);
        cp0_pagemask_write(TLB_PAGE_MASK_16K);
        tlbwi();

        page_table_unlock(AS, true);
        return;
        
fail:
        page_table_unlock(AS, true);
        tlb_invalid_fail(istate);
}

/** Process TLB Modified Exception.
 *
 * @param istate        Interrupted register context.
 */
void tlb_modified(istate_t *istate)
{
        tlb_index_t index;
        uintptr_t badvaddr;
        entry_lo_t lo;
        entry_hi_t hi;
        pte_t *pte;
        int pfrc;

        badvaddr = cp0_badvaddr_read();

        /*
         * Locate the faulting entry in TLB.
         */
        hi.value = cp0_entry_hi_read();
        tlb_prepare_entry_hi(&hi, hi.asid, badvaddr);
        cp0_entry_hi_write(hi.value);
        tlbp();
        index.value = cp0_index_read();

        page_table_lock(AS, true);      
        
        /*
         * Fail if the entry is not in TLB.
         */
        if (index.p) {
                printf("TLB entry not found.\n");
                goto fail;
        }

        pte = find_mapping_and_check(badvaddr, PF_ACCESS_WRITE, istate, &pfrc);
        if (!pte) {
                switch (pfrc) {
                case AS_PF_FAULT:
                        goto fail;
                        break;
                case AS_PF_DEFER:
                        /*
                         * The page fault came during copy_from_uspace()
                         * or copy_to_uspace().
                         */
                        page_table_unlock(AS, true);                     
                        return;
                default:
                        panic("unexpected pfrc (%d)\n", pfrc);
                }
        }

        /*
         * Read the faulting TLB entry.
         */
        tlbr();

        /*
         * Record access and write to PTE.
         */
        pte->a = 1;
        pte->d = 1;

        tlb_prepare_entry_lo(&lo, pte->g, pte->p, pte->w, pte->cacheable,
            pte->pfn);

        /*
         * The entry is to be updated in TLB.
         */
        if ((badvaddr / PAGE_SIZE) % 2 == 0)
                cp0_entry_lo0_write(lo.value);
        else
                cp0_entry_lo1_write(lo.value);
        cp0_pagemask_write(TLB_PAGE_MASK_16K);
        tlbwi();

        page_table_unlock(AS, true);
        return;
        
fail:
        page_table_unlock(AS, true);
        tlb_modified_fail(istate);
}

void tlb_refill_fail(istate_t *istate)
{
        char *symbol = "";
        char *sym2 = "";

        char *s = get_symtab_entry(istate->epc);
        if (s)
                symbol = s;
        s = get_symtab_entry(istate->ra);
        if (s)
                sym2 = s;

        fault_if_from_uspace(istate, "TLB Refill Exception on %p",
            cp0_badvaddr_read());
        panic("%x: TLB Refill Exception at %x(%s<-%s)\n", cp0_badvaddr_read(),
            istate->epc, symbol, sym2);
}


void tlb_invalid_fail(istate_t *istate)
{
        char *symbol = "";

        char *s = get_symtab_entry(istate->epc);
        if (s)
                symbol = s;
        fault_if_from_uspace(istate, "TLB Invalid Exception on %p",
            cp0_badvaddr_read());
        panic("%x: TLB Invalid Exception at %x(%s)\n", cp0_badvaddr_read(),
            istate->epc, symbol);
}

void tlb_modified_fail(istate_t *istate)
{
        char *symbol = "";

        char *s = get_symtab_entry(istate->epc);
        if (s)
                symbol = s;
        fault_if_from_uspace(istate, "TLB Modified Exception on %p",
            cp0_badvaddr_read());
        panic("%x: TLB Modified Exception at %x(%s)\n", cp0_badvaddr_read(),
            istate->epc, symbol);
}

/** Try to find PTE for faulting address.
 *
 * The AS->lock must be held on entry to this function.
 *
 * @param badvaddr      Faulting virtual address.
 * @param access        Access mode that caused the fault.
 * @param istate        Pointer to interrupted state.
 * @param pfrc          Pointer to variable where as_page_fault() return code
 *                      will be stored.
 *
 * @return              PTE on success, NULL otherwise.
 */
pte_t *
find_mapping_and_check(uintptr_t badvaddr, int access, istate_t *istate,
    int *pfrc)
{
        entry_hi_t hi;
        pte_t *pte;

        hi.value = cp0_entry_hi_read();

        /*
         * Handler cannot succeed if the ASIDs don't match.
         */
        if (hi.asid != AS->asid) {
                printf("EntryHi.asid=%d, AS->asid=%d\n", hi.asid, AS->asid);
                return NULL;
        }

        /*
         * Check if the mapping exists in page tables.
         */     
        pte = page_mapping_find(AS, badvaddr);
        if (pte && pte->p && (pte->w || access != PF_ACCESS_WRITE)) {
                /*
                 * Mapping found in page tables.
                 * Immediately succeed.
                 */
                return pte;
        } else {
                int rc;
                
                /*
                 * Mapping not found in page tables.
                 * Resort to higher-level page fault handler.
                 */
                page_table_unlock(AS, true);
                switch (rc = as_page_fault(badvaddr, access, istate)) {
                case AS_PF_OK:
                        /*
                         * The higher-level page fault handler succeeded,
                         * The mapping ought to be in place.
                         */
                        page_table_lock(AS, true);
                        pte = page_mapping_find(AS, badvaddr);
                        ASSERT(pte && pte->p);
                        ASSERT(pte->w || access != PF_ACCESS_WRITE);
                        return pte;
                        break;
                case AS_PF_DEFER:
                        page_table_lock(AS, true);
                        *pfrc = AS_PF_DEFER;
                        return NULL;
                        break;
                case AS_PF_FAULT:
                        page_table_lock(AS, true);
                        printf("Page fault.\n");
                        *pfrc = AS_PF_FAULT;
                        return NULL;
                        break;
                default:
                        panic("unexpected rc (%d)\n", rc);
                }
                
        }
}

void
tlb_prepare_entry_lo(entry_lo_t *lo, bool g, bool v, bool d, bool cacheable,
    uintptr_t pfn)
{
        lo->value = 0;
        lo->g = g;
        lo->v = v;
        lo->d = d;
        lo->c = cacheable ? PAGE_CACHEABLE_EXC_WRITE : PAGE_UNCACHED;
        lo->pfn = pfn;
}

void tlb_prepare_entry_hi(entry_hi_t *hi, asid_t asid, uintptr_t addr)
{
        hi->value = ALIGN_DOWN(addr, PAGE_SIZE * 2);
        hi->asid = asid;
}

/** Print contents of TLB. */
void tlb_print(void)
{
        page_mask_t mask;
        entry_lo_t lo0, lo1;
        entry_hi_t hi, hi_save;
        unsigned int i;

        hi_save.value = cp0_entry_hi_read();
        
        printf("#  ASID VPN2   MASK G V D C PFN\n");
        printf("-- ---- ------ ---- - - - - ------\n");
        
        for (i = 0; i < TLB_ENTRY_COUNT; i++) {
                cp0_index_write(i);
                tlbr();
                
                mask.value = cp0_pagemask_read();
                hi.value = cp0_entry_hi_read();
                lo0.value = cp0_entry_lo0_read();
                lo1.value = cp0_entry_lo1_read();
                
                printf("%-2u %-4u %#6x %#4x %1u %1u %1u %1u %#6x\n",
                    i, hi.asid, hi.vpn2, mask.mask,
                    lo0.g, lo0.v, lo0.d, lo0.c, lo0.pfn);
                printf("                    %1u %1u %1u %1u %#6x\n",
                    lo1.g, lo1.v, lo1.d, lo1.c, lo1.pfn);
        }
        
        cp0_entry_hi_write(hi_save.value);
}

/** Invalidate all not wired TLB entries. */
void tlb_invalidate_all(void)
{
        ipl_t ipl;
        entry_lo_t lo0, lo1;
        entry_hi_t hi_save;
        int i;

        hi_save.value = cp0_entry_hi_read();
        ipl = interrupts_disable();

        for (i = TLB_WIRED; i < TLB_ENTRY_COUNT; i++) {
                cp0_index_write(i);
                tlbr();

                lo0.value = cp0_entry_lo0_read();
                lo1.value = cp0_entry_lo1_read();

                lo0.v = 0;
                lo1.v = 0;

                cp0_entry_lo0_write(lo0.value);
                cp0_entry_lo1_write(lo1.value);
                                
                tlbwi();
        }
        
        interrupts_restore(ipl);
        cp0_entry_hi_write(hi_save.value);
}

/** Invalidate all TLB entries belonging to specified address space.
 *
 * @param asid Address space identifier.
 */
void tlb_invalidate_asid(asid_t asid)
{
        ipl_t ipl;
        entry_lo_t lo0, lo1;
        entry_hi_t hi, hi_save;
        int i;

        ASSERT(asid != ASID_INVALID);

        hi_save.value = cp0_entry_hi_read();
        ipl = interrupts_disable();
        
        for (i = 0; i < TLB_ENTRY_COUNT; i++) {
                cp0_index_write(i);
                tlbr();
                
                hi.value = cp0_entry_hi_read();
                
                if (hi.asid == asid) {
                        lo0.value = cp0_entry_lo0_read();
                        lo1.value = cp0_entry_lo1_read();

                        lo0.v = 0;
                        lo1.v = 0;

                        cp0_entry_lo0_write(lo0.value);
                        cp0_entry_lo1_write(lo1.value);

                        tlbwi();
                }
        }
        
        interrupts_restore(ipl);
        cp0_entry_hi_write(hi_save.value);
}

/** Invalidate TLB entries for specified page range belonging to specified
 * address space.
 *
 * @param asid          Address space identifier.
 * @param page          First page whose TLB entry is to be invalidated.
 * @param cnt           Number of entries to invalidate.
 */
void tlb_invalidate_pages(asid_t asid, uintptr_t page, count_t cnt)
{
        unsigned int i;
        ipl_t ipl;
        entry_lo_t lo0, lo1;
        entry_hi_t hi, hi_save;
        tlb_index_t index;

        ASSERT(asid != ASID_INVALID);

        hi_save.value = cp0_entry_hi_read();
        ipl = interrupts_disable();

        for (i = 0; i < cnt + 1; i += 2) {
                hi.value = 0;
                tlb_prepare_entry_hi(&hi, asid, page + i * PAGE_SIZE);
                cp0_entry_hi_write(hi.value);

                tlbp();
                index.value = cp0_index_read();

                if (!index.p) {
                        /*
                         * Entry was found, index register contains valid
                         * index.
                         */
                        tlbr();

                        lo0.value = cp0_entry_lo0_read();
                        lo1.value = cp0_entry_lo1_read();

                        lo0.v = 0;
                        lo1.v = 0;

                        cp0_entry_lo0_write(lo0.value);
                        cp0_entry_lo1_write(lo1.value);

                        tlbwi();
                }
        }
        
        interrupts_restore(ipl);
        cp0_entry_hi_write(hi_save.value);
}

/** @}
 */